I had previously said i planned to be there around 11 am and some people said the same

I don't mind having a meetup time later if people have further to travel, but I still plan to be there late morning in order to make best use of the time I am happy to PM a phone number for people wanting a contact - as it happens I have found my Oly hat so that should help people locate me

You are right that we need to keep an eye on the weather - at present it is forecast to be overcast that day. Not perfect, but not awful either

Just a thought. Once people are parked up you'll probably need to queue to pay to get in (entrance circled in red). Most visitors go off to the right from there to start their visit or wait for a guided tour to start.

Would the clump of trees to the left of the entrance (highlighted in blue) be a good place to meet up?